The guinea pig model has been employed for the assessment of acute respiratory responses to chemically-treated cotton dusts. Dusts treated with ethanolic solutions containing NaOH have shown decreased respiratory toxicity. In this study, additional treatments were assessed for their potential as detoxifying processes. Treatments included use of dimethyl sulfoxide, detergent, and ethanol containing acid or base. Endotoxin levels, as assessed using Limulus amebocyte lysate (LAL), were lower in treated compared with untreated dusts; the sample with detergent additive was the only exception. Animals were exposed to treated dusts for six hours with pulmonary function monitored pre, immediately post and 24 hour post-exposure. The ethanol with base treatment was the most effective in reducing acute respiratory toxicity confirming previous findings. Lack of consistent correlation between apparent endotoxin content and respiratory responses indicated that the LAL assay cannot be used to predict the level of respiratory toxicity of treated cotton dusts.